输电塔线体系在摇摆地震动作用下的动力稳定性分析

为探究摇摆分量对输电塔线体系动力稳定性能的影响，以一实际输电塔为原型进行了动力时程分析，其中摇摆地震动采用改进的谱比法由地震平动中获取；根据增量动力分析(incremental dynamic analysis, IDA)方法结合B-R准则，分别对塔线体系在水平地震作用、水平-摇摆耦合地震作用和水平-竖向-摇摆耦合地震作用下的动力稳定性能进行分析。研究结果表明：摇摆分量及其引起的附加P-Δ效应会使输电塔线体系产生非对称振动，结构发生偏离平衡位置的单向偏移，从而导致塔线体系较仅考虑水平地震作用，更易动力失稳；重力和竖向地震响应下共同的二阶效应，放大了摇摆分量对结构动力稳定性能的影响，加剧输电塔线体系动力失稳破坏；发生动力失稳破坏时，薄弱区域主要集中于塔身中下部，杆件失效使塔身局部变形过大，导致塔线体系发生整体动力失稳。

Analysis of dynamic stability of a transmission tower-line system under tilt ground motion

To explore the influence of tilting ground motion to the dynamic stability of a transmission tower-line system, the dynamic time history analysis of an actual transmission tower was carried out. Based on incremental dynamic analysis(IDA) method and the B-R criterion, the dynamic stability of the tower line system under horizontal seismic, horizontal coupled tilting and horizontal, vertical coupled tilting ground motion was analyzed. Results indicate that the rocking component and its additional second order effects of gravity produce asymmetric vibration to the transmission tower-line system, the structure has a one-way deviation from the equilibrium position, and makes the tower system more prone to dynamic instability than considering horizontal ground motion only. The influence of rocking component on the dynamic stability performance of the structure is amplified by second-order effect caused from gravity and vertical seismic response, which intensifies the dynamic instability and failure of the transmission tower-line system. When dynamic instability occurs, the weak area is mainly concentrated in the middle and lower part of the tower body, and the failure of the bar makes the local deformation of the tower body too large, leading to the whole dynamic instability of the tower-line system.